Lotus Elan

light is right... but which light ? metallurgy question

PostPost by: promotor » Thu Jul 18, 2019 11:52 am

2cams70 wrote:What size bolts have they provided with the flange? You may be able to Helicoil the flange with threads. Ed. Sorry - why would you Helicoil? Just tap!!

Might work out a better idea to Helicoil as just tapping out to a size that uses the original core size of the hole will likely mean going out to a bigger bolt which will probably have the knock on effect that the new threaded bolt won't pass through the propshaft flange holes once done. Helicoil might give the room needed to still be able to use the original size shank / shoulder on the bolt and not take any material out of the propshaft flange.

I've not looked at Helicoil sizes involved but could be worth investigating.
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PostPost by: 2cams70 » Thu Jul 18, 2019 12:09 pm

I think if it were me I'd just replace the flange with on OEM one - now how often have I done that - replace with OEM parts!!! At least we have a range of possible solutions now:

1. Reverse bolt so nut is on outside
2. Helicoil flange.
3 And - Wait for it..... Pull out the trusty grinder and exorcise that offending expensive aluminium right off!!!
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PostPost by: patrics » Thu Jul 18, 2019 3:53 pm

If I remember correctly then it either:
fouls which ever way you bolt it
or you can not get the bolt in

This a standard size flange supplied by TTR
In the end I just cut away the alloy
Helicoil Really? not much meat there.
Nut and bolt is far better in this application - far easier to work on
Obviously I could have brought TTR casing (more expensive) but didn't appreciate the consequences.

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PostPost by: gus » Wed Aug 21, 2019 8:50 pm

TO helicoil you need a minimum of 3 complete threads, ten allowance for a chamfer on each side.

for a 20 tpi, .05x3+~.075= .225 in


I think I would rather cut a bolt head down
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PostPost by: baileyman » Thu Aug 22, 2019 1:02 am

2cams70 wrote:Those things are so expensive compared to the weight saving!! ...

And that is quite true. I'll tell ya though, what I do appreciate is being about to hoist the various light castings fully assembled with my bare hands in the garage, whether or not they actually make a performance difference. Who is it, Col?, who has a video on diff changing? If I ever want to be swapping ratios like that, it'll be mag/aluminum all the way.
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